#!/usr/bin/env bash

################################################################################
# Runs pytest on files that have been modified.
#
# Usage:
#     check/pytest-changed-files [BASE_REVISION] [--pytest-flags]
#
# This tool is not clever; it does not understand dependencies between all
# files. If "x.py" or "x_test.py" have been modified, it will include
# "x_test.py" in the arguments given to pytest. That's all it does.
#
# You can specify a base git revision to compare against (i.e. to use when
# determining whether or not a file is considered to have "changed"). To make
# the tool more consistent, it actually diffs against the most recent common
# ancestor of the specified id and HEAD. So if you choose 'origin/main' you're
# actually diffing against the output of 'git merge-base origin/main HEAD'.
#
# If you don't specify a base revision, the following defaults will be tried,
# in order, until one exists:
#
#     1. upstream/main
#     2. origin/main
#     3. main
#
# If none exists, the script fails.
#
# You can pass flags such as "-v" into pytest by placing them after the
# comparison id.
################################################################################

# Get the working directory to the repo root.
thisdir=$(dirname "${BASH_SOURCE[0]:?}") || exit $?
repo_dir=$(git -C "${thisdir}" rev-parse --show-toplevel) || exit $?
cd "${repo_dir}" || exit $?

# Figure out which revision to compare against.
rest=( "$@" )
if [ -n "$1" ] && [[ $1 != -* ]]; then
    if ! git rev-parse --verify --quiet --no-revs "$1^{commit}"; then
        echo -e "\033[31mNo revision '$1'.\033[0m" >&2
        exit 1
    fi
    rev=$1
    rest=( "${@:2}" )
elif [ "$(git cat-file -t upstream/main 2> /dev/null)" == "commit" ]; then
    rev=upstream/main
elif [ "$(git cat-file -t origin/main 2> /dev/null)" == "commit" ]; then
    rev=origin/main
elif [ "$(git cat-file -t main 2> /dev/null)" == "commit" ]; then
    rev=main
else
    echo -e "\033[31mNo default revision found to compare against. Argument #1 must be what to diff against (e.g. 'origin/main' or 'HEAD~1').\033[0m" >&2
    exit 1
fi
# fall back to ${rev} if it has no common ancestor with our branch
base=$(git merge-base "${rev}" HEAD) || base=$(git rev-parse "${rev}")

if [ "$(git rev-parse "${rev}")" == "${base}" ]; then
    echo -e "Comparing against revision '${rev}'." >&2
else
    echo -e "Comparing against revision '${rev}' (merge base ${base})." >&2
    rev="${base}"
fi

# Get the _test version of changed python files.
typeset -a changed
IFS=$'\n' read -r -d '' -a changed < \
    <(git diff --name-only "${rev}" -- \
    | grep "\.py$" \
    | sed -e "s/\.py$/_test.py/" \
    | sed -e "s/_test_test\.py$/_test.py/" \
    | perl -ne 'chomp(); if (-e $_) {print "$_\n"}' \
    | sort \
    | uniq \
)
if git diff --name-only "${rev}" -- | grep "__init__\.py$" > /dev/null; then
  # Include global API tests when an __init__ file is touched.
  changed+=('cirq-core/cirq/protocols/json_serialization_test.py')
fi
num_changed=${#changed[@]}

# Run it.
echo "Found ${num_changed} test files associated with changes." >&2
if [ "${num_changed}" -eq 0 ]; then
    exit 0
fi

source dev_tools/pypath || exit $?

pytest "${rest[@]}" "${changed[@]}"
